Method of and system for radiosignaling



Sept. 16, 1930. E; L. CHAFFEE 1,776,065

METHOD OF AND SYSTEM FORRADIOSIGNALING Filed Aug. 29. 1322 MflDUL A TORawvemtoz Patented Sept. 16, 1930 EMORY LEON CHAFFEE, OF BELMONT,MASSACHUSETTS, ASSIGNOR TO JOHN HAYS HAMMOND, JR., 0F GLOUCESTER,MASSACHUSETTS METHOD OF AND SYSTEM FOR RADIOSIGNALING Application filedAugust 29, 1922. Serial No. 584,959.

This invention relates to methods of and systems for transmittingintelligence by radiant energy and has for some of its objects theprovision of an improvedmethod and means for transmitting a messagewithout interference by others; the elimination of effects of static andother atmospheric strays; and the provision of a plurality of messagechannels over which the message may be transmitted in variouslycharacterized forms, whereby the message may be transmitted over any ofthe channels independently of the other or others. Still other objectsof the invention will appear hereinafter.

In the drawings there is shown diagrammatically so much of a radiosystem embodying the present invention as is necessary to anunderstanding of the present invention.

Fig. 1 represents a transmitter and Fig. 2 represents a receiver.

In systems for radiant signaling it has been the practice to providemeans at the sending station for modulating a fundamental frequency orcarrier wave, commonly known as the A frequency, by a second oscillatingcurrent commonly designated the B frequency. The B frequency current maybe a current of voice frequency, that is, may be produced by a usualtelephone transmitter in accordance with voice waves. It is understoodthat the system of the present invention may employ such a sender whichis shown, for example, in Fig. 1, provision being made for theproduction of a plurality of A frequency currents 1, 2, etc, ofrelatively different frequencies, all modulated in accordance with thesame B frequency. In the specific embodiment shown and described for thepurpose of illustration a pair of channels is provided and it isunderstood that the phase of modulation at the sender is to be oppositeso that the modulation frequency efiects at the receiving stationare'additive, in the filter circuit. This will be more fully brought outin the following detailed description of the receiving apparatus.

Referring to Figure 2, there is shown so much of a so-called wirelessreceiving systern as 1s necessary to an understandmg of the invention.As shown, the sald recelvlng denser 13, by which it may be tuned to oneof the A frequencies. The circuit 12 of the loop 10 is operativelyconnected to a three electrode thermionic device 14 having a usualheated filament 15 forming a hot cathode for emitting electrons, a plate16 upon which the electrons impinge, and a grid or potential gradientvarying means 17 for controlling the passage of electrons. The grid orinput circuit is thusarranged to be controlled by electricaloscillations in theloop 10 and. the oscillatory circuit 12. In serieswith the grid or input circuit there is provided a blocking condenser 21and a usual grid leak resistance whereby the device 14 is caused tooperate as a detector.

Similarly, the loop 11 forms part of a closed oscillatory circuit 18,including an adjustable condenser 19 by which it may be tuned to theother one of the A frequencies. The circuit 18 of the loop 11 isoperatively connected to a second'three-electrode' thermionic device 20similar to the device 14 and having a usual filament 15, plate 16 andgrid 17. The grid or input circuit of the device 20 is arranged to beresponsive to the electrical oscillations in the loop 11 and closedoscillatory circuit 18. In series with the grid circuit there isprovided a blocking condenser 22 and usual grid leak resistance wherebythe device 20 is caused to operate as a detector. A-filament heatingbattery 23 serves to incandesce the filaments '15 of the thermionicdevices 14 and 20.

The output circuit of the thermionic device 14 includes a winding 30 ofa transformer 31 and a plate potential battery 32. The output circuit ofthe thermionic device 20 includes another winding 33 of thetransformer31 and also the plate potential battery 32. The plate potential batter32 determines thenormal plate voltage the plates 16.of the devices-14'and 20, its polarity being such that said plates are positive withrespect to the hot cathodes. A

third winding 34 of the transformer 31 forms part of a filter orresonant circuit 35 which as shown includes a suitable condenser 36 anda winding 37 of a second transformer 38. The capacity of the condenser36and the inductance of the windings 34 and filament 15 and plate'16. Afilament heating battery 42 is arranged to incandesce the filament 15. Acondenser 43 is provided in the grid or input circuit of the device 41for a purpose which will be subsequently set forth. The output or platecircuit of the thermionic device 41 includes an indicating device 44, aplate potential battery 45, and a winding 46 of a transformer 48. Thepotential of battery is such that the plate 16 of the device 40 is madepositive with respect to the hot cathode. A by-pass condenser 47 isprovided in shunt with the indicating device 44 for currents ofrelatively high frequency. The secondary winding 49 of the transformer48 is included in the grid circuit of the device 41 for feeding backenergy thereto. 1

nthe operation of the embodiment shown in Figure 2 the sending stationimpresses on the ether a plurality of fundamental or A frequencies,differing from each other and modulated in accordance with the same Bfrequency current which may be super audible or may be an ible as invoice modulation). -The respective oscillations produce currents in thecoils 10 and 11, and these currents are respectively rectified ordetected by means of the thermionic devices 14 and 20. .The rectified ordetected currents flow through the respective windings I 30 and 33 ofthe transformer 31, the direction of winding being such that theyproduce additive effects upon the winding 34.

A local currentflows in the filter circuit 35 I 'which is inductivelycoupled to igqe winding 40 of the transformer 38 and t s to the inputcircuit ofthe thermionic device 41. The windings 46 and 49 are arrangedso that energy is fed back from the plate or outplut circuit of theamplifying device 41 to t e input or grid circuit. If the modulationfrequency is super audible device 41 isvused as an autodyne. Thefrequency of the current fed back is then such that it dif fers from thefrequency of current flowing in the filter circuit 35, by a relativelysmall amount, there being thus produced a series of beats which aresufliciently low in fre-' .ing 40.

It will be seen that the effects of the true message currents areadditive in the circuit 35 while the effects of strays and staticdisturbances will be subtractive. true message will'be reliably receivedwith substantially no interference thereto by strays or staticdisturbances, or by other. interfering messages.

Thus it will be seen that I have provided a receiving system forreceiving telephone or telegraph messages which is-essentially proofagainst interference from atmospheric stra s or so-called static orother radio .distur ances. Furthermore, the system provides two channelsthrough either of which the message is received, each of said channelsbeing adapted to receive the message independently. Danger of block bymalicious outsiders is thus minimized since each of the Thus thechannels will operate independently of such outside interference toactuate the indicating device, and thus the message will be received inspite of the attempted interference. Furthermore, the system isrelatively free from 00 interference by strays or so-called stat1c. 1

Illustrative apparatus and circuits have been shown for the purpose ofshowing some of the ways in'which the invention may be practiced; but itis expressly understood that the scopeof the invention is not to belimited thereby, reference being had to the appended claims for thatpurpose.

What is claimed is 1. A method of electrical communication whichconsists in transmitting two series of wavesmodulated in opposite phaserelation, receiving said series'of waves, producing at the receivercurrents corresponding in frequency with said modulations, additivelycombining said currents, and indicating them.

'2. A method of electrical communication which consists in transmittingtwo series of waves modulated in opposite phase relation, impressingsignal variations on the modulated series of waves, receiving saidseries of waves, producing at the receiver currents phase for each ofsaid series of oscillations,

means for demodulating said series of oscillations to produce currentscorresponding 1n frequency with the modulations thereof,

means for additively combining said currents, an indicating device, andmeans for causing said combined currents to actuate said device.

A. A radio receiving system comprising two channels for the receptionrespectively of two carrier waves having unlike frequencies andmodulated in opposite phase relation, a detector operatively connectedwith each of said channels, an indicating device operated by saiddetectors, and a filter circuit connected oppositely to the outputcircuits of the detectors and interposed between said detectors and saidindicating device for permitting the "passage of currents of a selectedfrequency band.

5. A radio receiving system comprising a plurality of channels for thereception of a plurality of carrier waves having unlike frequencies andmodulated at the same fre quency but in different phase relation, adetector operatively connected with each of said means, an indicatingdevice operated by said detectors, and a single filter circuitdifferentially connected with the output sides of the detectors andinterposed between said detectors and said indicating device, said fil-vter circuit being responsive only to a predetermined frequency band.

6. A multi-channel radio receivingvsystein comprising a pair of loopsarranged at an iii) angle of substantially 90 to each other and atangles of substantially 45 to the direction of propagation of a signalwave, a corresponding pair of closed, oscillatory circuits eachincluding one of said loops, a detector operat'ively connected with eachof said closed, oscillatory circuits, an indicating device operated bysaid detectors, and a filter circuit interposed between said detectorsand said indicating device.

7. In a receiving system for radiant energy, a plurality of receivingchannels tuned to energy of difierent frequencies respectively, meansfor producing currents of like frequencies but of different phases fromthe received energy, an indicating device, and

means interposed between said channels and the indicating device forcausing said currents to combine additively and to simultaneouslyactuate said device.

- 8. A method of wireless communication which consists in transmittingtwoseries of waves having unlike frequencies and modulated in oppositephase relation according to a single series of variations impressedthereon, receiving and detecting the energy of each of said wavesindependently, additively combining the currents produced by saiddetection, combining the resultant current-with current of a differentfrequency to produce beat currents, and indicating the beat currents.

9. Means for receiving the energy of a plurality of waves modulated inout-of-phase relation accordingto a single series of variations,comprising an indicating device, means for producing currents from saidwaves of frequencies corresponding to said variations and of similarout-of-phase relation, and means for additlvely combining said currentsto actuate said device and for differentially combining the effects ofother waves.

10. Means for receiving the energy of two waves modulated in oppositephase relation according to a single series of variations, comprising anindicating device, means for producing currents from said waves offrequencies corresponding to said variations and of opposite phaserelation, and means for additively combining the energy of said waves toactuate said device and for differ entially combining the effects ofother waves.

11. Radio receiving apparatus selectively responsive to the energy oftwo Waves difiering in a frequency characteristic and each modulated inopposed phase relation by a single signal current, comprising anindicating device, means for producing currents from said waves offrequencies corresponding to the frequencies of modulations of thewaves, means for impressing said currents on the indicating devicecumulatively, and

means for differentially combining the energy of waves otherwisemodulated to effectively prevent the actuation of said device thereby.

12. Radio receiving apparatus selectively responsive to the energy oftwo waves differing in a frequency characteristic and each modulated inopposed phase relation by a single signal current, comprising anindicating device responsive to the energy of such waves, means forproducing current from said waves of frequencies corresponding to thefrequencies of modulations of the waves, means for causing said currentsto operate the indicating device, and means for differentially combiningthe energy of waves otherwise modulated to effectively prevent theactuation of the indicating device thereby.

13.- A method of electrical communication which consists in transmittinga plurality of series of waves modulated in out-of-phase relation,receiving said series of waves, producing at the receiver currentscorresponding in frequency with said modulations respectively andadditively combining said currents to produce a signal, butdifferentially combining the energy of waves not so characterized.

14. A method of electrical communication which consists in transmittingtwo series of waves modulated in out-of-phase relation, receiving saidseries of waves, producing at the receiver currents corresponding infrequency with said modulations respectively and additively combiningsaid currents to produce a signal, but difierentially combining theeffects of static.

15. In a system of radio communication, 7

a pair of radio transmitters of difierent radio frequencies, modulatingmeans afi'ecting the two transmitters in opposite senses, means forradiating differentially modulated waves *of the two frequencies,receiving and integrating means discriminating between the twotransmitted frequencies and means for applying the integrated currentsin opposite senses to a common receiver whereby the difierentialmodulation acts cumulatively on the receiver.

16. In a transmitting system for radiant energy, two radio frequencygenerators simultaneously emitting waves of different frequencies, atelephone transmitter, and means operated by the telephone transmitterfor modulating the two transmitted waves simultaneously in oppositesenses.

17. The method of transmitting and receiving radio intelligence whichconsists in generating and radiating two waves of different radiofrequencies, modulating these waves 1n opposlte sense, separatelyrecervmg the waves of different frequencies and combining their effectsin opposite senses to produce a cumulative result.

In testimony whereof I hereunto afiix my signature.

EMORY LEON CHAFFEE,

